Non-volatile memory cells are widely used because they can store data even when the power supply is cut off. Generally, non-volatile memory cells can be sub-classified into two types, floating-gate structure and SONOS structure. The floating-gate structure utilizes source side injection (SSI) or tunneling effect leading hot electrons stored in the floating gate. However, the application of the floating-gate structure is increasingly difficult day after day, because of the hot electrons punching through along the select gate channel as the source-drain channel length shrinks. In comparison with the floating-gate structure, the SONOS structure which also leads hot electrons stored in a silicon nitride layer can be manufactured in a smaller size. Therefore, there is a prevailing tendency today to replace the floating-gate structure with the SONOS structure.
However, to avoiding adjacent two SONOS non-volatile memory cells overlapping with each other during the manufacturing process for forming an electric device involving a plurality of SONOS non-volatile memory cells, some dimension tolerance is usually reserved in the layout pattern of the electronic device to meet the process margin resulted from the prior manufacturing method. Thus it is hard to decrease the distance between the two adjacent SONOS non-volatile memory cells and the device integrity may not be increased.
Therefore, it is necessary to provide an advanced method for fabricating a SONOS non-volatile memory cell to obviate the drawbacks and problems encountered from the prior art.